China.China · a luminous spiral seen across 14 provinces

Around 10:33 p.m. on July 24, 1981, a bright, star-like point appeared in the sky over northern and central China and began to open into a "cloud-like" luminous spiral band. The spiral expanded for about six or seven minutes, and the phenomenon had faded by about 10:53 p.m. It was seen at the same time across as many as 14 provinces and cities, and estimates speak of hundreds of thousands of witnesses. Sixth Tone, by contrast, puts it at about 10:40 p.m., names the western provinces of Gansu, Sichuan and Yunnan, and describes a spiral that spun as it moved slowly from east to west. The shape was that of a spiral opening out from a central core and smearing out like smoke.

Two astronomers at the Purple Mountain (Zijinshan) Observatory of the Chinese Academy of Sciences studied the case. Wang Sichao, a planetary astronomer, collected more than seventy witness accounts over the years and spent more than two decades on this and other sightings. He held that the object moved in a way that did not fit a natural body, and throughout his career he argued that some Chinese sightings deserved an "intelligent, non-natural" explanation.

In 1981, Wang took his colleague Liu Yan to meet students from Wuhan University who represented the China UFO Research Association. The press at the time had carried another reading, attributed to astronomers: meteoroids from a Cassiopeia meteor shower; according to Sixth Tone, many experts disagreed. After reviewing the witness accounts, Liu concluded that the object was likely a man-made craft at an altitude of about 650 km, and published his analysis in the magazine Amateur Astronomer; it was his first article on UFOs. As he explained to Sixth Tone, with the apparent position and size of an object seen from more than two different places, one can calculate its true distance, its size and its average speed. Later press credits Wang with reconstructing the trajectory, with that altitude and a speed of about 1.6 km/s before it disappeared, but according to Sixth Tone the 650 km figure comes from Liu.

At 650 km, far above any aircraft or atmospheric phenomenon, the spiral fits a mechanism well known in spaceflight: a rocket stage or satellite releasing leftover fuel or gases as it spins, forming a spiral lit by the Sun against an already dark sky (the so-called "twilight effect"). It is the phenomenon later confirmed behind the 2009 Norway spiral, the failed launch of the Russian Bulava missile, and behind several later Chinese "UFO spirals" officially attributed to launches; in one of them, when a sounding rocket was mistaken for a UFO, the press quoted Wang himself. The 1981 spiral, by contrast, was never tied in the public record to a specific, dated and named launch: the mechanism is confirmed in similar cases, but no record closes this one.

Hundreds of thousands of people saw the spiral across whole provinces. That number says how many people were looking at the sky that night and from how far away the object could be seen, not what caused it: an object at about 650 km is visible at once from an immense area, which is why so many saw it.

The two Purple Mountain Observatory astronomers who studied the spiral reached different readings. Wang Sichao, the one most associated with the case, held that the object moved in a way that did not fit a natural body, and argued for non-natural readings of several Chinese sightings. His colleague Liu Yan, after reviewing the witness accounts, attributed it to a man-made craft. The spiral shape, together with the altitude, fits the fuel released by a rocket or satellite, although the specific launch remains unidentified.